Well, I figure they were kinda already qualified for "people who are interested in reading webcomics" as I was only advertising on other webcomics in the first place. Guess I should have mentioned that.

My stats suggested that a pretty decent percentage of people read a good chunk of what's online and subscribed to it. Which ain't paying my bills yet but the ads are self-supporting now, and slowly growing. Or they were until I had to take the site down because malware. (Any HNers interested in building me a site that's more secure than "a Wordpress theme designed for comics"?)